Plivo core architecture - how is call stalled waiting on HTTP response

devsupport

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Dec 22, 2012, 10:23:08 AM12/22/12

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I was just curious to know how Plivo bolts on to FS. I have looked at the Github source files and see many python based scripts that glean off the event sockets. Is that the case? Is the core of Plivo a ESL wacther?

If that is the case then how do you basically "stall" FS from dipping into the dialplan waiting for a slower HTTP system to reply back?. In other words, say a call comes in, normal FS response is to dip into the dialplan with ESL still operating. So in Plivo how do you prevent FS from sniffing at the dialplan.

Thank

DS

Mitul Limbani

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Dec 22, 2012, 11:48:46 AM12/22/12

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Ideally plivo answer url needs to be in same physical infrastructure as fs, to avoid the situation that you are visualizing.

FS wont sniff in, it would just hangup the call if answer url timesout.

Mitul

devsupport

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Dec 22, 2012, 4:41:14 PM12/22/12

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Sorry for using the word sniff here. :).

I fully understand the role of Plivo on an outbound call. You can initiate a call and then control every bit of it because the call is established and FS really never needs a diaplan.

What I was wanting to know is what Plivo is actually doing behind the scenes on an inbound call. By default FS will look up for a dialplan as soon as a call comes in. So how does Pilvo prevent that native behavior. Does installing Pilvo disable that native behaviour. If so, how does it do it.

DS

devsupport

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Dec 22, 2012, 5:04:52 PM12/22/12

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Also what is the timeout period for a response before FS hangs up the call? Is that fixed or can that be changed?

DS

devsupport

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Dec 22, 2012, 7:09:38 PM12/22/12

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I think I have figured out the answer by basically wiresharking a simple dial. From my tests it looks like when a call arrives to Plivo it will by default send out a SIP 183. That in itself gives unlimited time to wait.

So basically what I think is the Pilvo core is a simple dialplan to just "Pre-Answer". That basically sets up the calland it stays there. Once thats done you can work with the call via ESL and take you own sweet time.

Perfect plan. However, I hope Plivo engineering can confirm this as being correct.